1. Field of the Invention
The present invention relates to an electronic apparatus such as a portable computer or a wordprocessor and, more particularly, to a structure for increasing the number of optional units such as a compact disk drive and a hard disk drive which can be installed in the case of an electronic apparatus.
2. Description of the Related Art
Various types of high-performance laptop portable computers which can be easily carried have recently been provided. A computer of this type comprises a base unit having a keyboard, and a flat panel type display unit which is mounted on the base unit to be freely opened/closed. The base unit has a case consisting of a synthetic resin material. Functional units such as a floppy disk drive and a power supply unit and a circuit board on which various types of circuit parts such as IC chips are mounted are housed in this case.
In order to prevent an electrical shock and a failure, the case of a conventional computer is designed on the assumption that the case is not disassembled. The above circuit board and functional units are supported on the bottom surface of the case. The circuit parts mounted on the circuit board include parts which generate high-frequency noise while they are in operation. It is known that when this high-frequency noise leaks outside the case, an electric wave trouble or a communication trouble may be caused. For this reason, the inner surface of the case is plated with a conductive material or the circuit board is enclosed with a metal shield plate.
Since a computer of this type is used in a variety of applications, it often has only the minimum necessary functions required for the operation of a computer. For this reason, various types of optional units for functional expansion such as a large-capacity hard disk drive, an expansion card, and a modem unit for communication are prepared for a conventional computer. Such a computer is designed to selectively mount these optional units in accordance with application purposes. More specifically, a storage space for storing optional units is partly ensured in the rear or side portion of a case. This storage space has insertion ports formed in the bottom or rear surface of the case. Each insertion port is closed by a detachable cover.
According to this arrangement, however, since a storage space for optional units is partly formed in the interior of the case, the case requires partition walls to define the storage space. For this reason, the structure of the case is complicated, and the manufacturing cost increases. The interior of the case is narrowed because of the presence of the partition walls, and escapes for bypassing the partition walls must be provided for a circuit board. In addition, the partition walls interfere with arrangement of various components.
As the number of optional units which can be additionally mounted increases, a larger number of storage spaces must be ensured in the case. Therefore, the number of storage spaces may be limited depending on the size of a case. Consequently, a large number of optional units cannot be additionally mounted, interfering with an improvement in the performance of the computer.
On the other hand, a large-capacity power supply unit and a CPU are housed in the case of the computer. The power supply unit and the CPU generate a large amount of heat while they are in operation. If the heat generated by the power supply unit and the CPU remains in the case, peripheral circuit components are greatly affected by the heat. For this reason, as disclosed in U.S. Pat. No. 4,479,198 issued to Romamo et al., Oct. 23, 1984, a computer having a functional component generating a large amount of heat is designed such that an inlet port for drawing outer air and an exhaust port for exhausting the drawn outer air are formed in a side surface of a case, and a cooling fan is arranged in the case to forcibly cool the functional component.
In addition, as disclosed in U.S. Pat. No. 5,199,888 issued to Condra et at., Apr. 6, 1993, a high-performance computer includes a plurality of expansion connectors for connection of various peripheral devices such as a printer and an external keyboard. These expansion connectors are arranged on a side or rear surface of a case. The expansion connectors are covered with a connector cover while no peripheral devices are connected. This connector cover is supported on the case to be movable between a closing position at which the expansion connectors are covered and an opening position at which the expansion connectors are exposed to the outside of the case.
In the computer having the above arrangement, if expansion connectors are arranged adjacent to the inlet port or the exhaust port formed in the case, when the connector cover is moved to the opening position, the connector cover may overlap the inlet port or the exhaust port. In this case, the inlet port or the exhaust port is closed by the connector cover, and the ventilation in the case is impaired. For this reason, the functional component which generates heat cannot be efficiently cooled.
As a portable computer, a computer having a speaker for outputting an alarm or warning as a sound during an operation of software is known. The speaker has a speaker frame supporting a cone. This speaker frame is supported on the inner surface of the case.
Various functional components such as a floppy disk drive as well as a circuit board are arranged in the case. In addition, since the internal space of the case is limited, the circuit board, the functional components, and the speaker are arranged to be adjacent to each other. For this reason, when the speaker frame is mounted in the case, the fragile cone may interfere with and may be damaged by the circuit board or a functional component, thus posing a problem in mounting the speaker in the case.
The types of portable computers capable of mounting interface cards for communication with external units and application cards storing application programs have been increasing. A computer capable of mounting such a type of card has a card storage portion in the case. This card storage portion has a card insertion port formed in a side surface of the case. A connector to which the card is detachably connected is arranged in the card storage portion. The connector is located at the opposite side to the card insertion port.
The card storage portion has an ejector for guides a card, inserted from the card insertion port, to the connector, and for ejecting the card from the card storage portion. The ejector has a push button to be depressed with a finger tip of an operator when the card is to be removed. The push button is exposed to the card insertion port and is located adjacent to the rear end portion of the card stored in the card storage portion.
According to this arrangement, however, since the push button is exposed to the card insertion port and can be depressed at any time, the push button may be erroneously depressed during an operation of the card. In order to prevent this, a known computer is designed such that a lock pawl which is locked to the trailing end of a card inserted from the card insertion port of the case is arranged at the card insertion port. According to this arrangement, since the card is locked/held in the card storage portion by the lock pawl, even if the push button is erroneously depressed during an operation of the card, removal of the card from the card storage portion can be prevented.
On the other hand, if the card needs to be removed and an operator forgets that the card is locked by the lock pawl, he/she may depress the push button hard. As a result, an excessive force is applied to the ejector, causing an ejector failure or damaging the ejector.
If a computer of this type has first and second card storage portions for loading a plurality of types of memory cards, in addition to the card storage portion for the interface card or the application card, a pair of card connectors to which memory cards are connected are arranged in the card storage portions, respectively. These card connectors are mounted on a main circuit board housed in the case.
In this case, in a computer having only one main circuit board, the pair of card connectors are laterally arranged on the main circuit board on the same plane. Consequently, the first and second card storage portions are also laterally arranged in the case.
According to this arrangement, however, since the first and second card storage portions are laterally arranged, the area occupied by the card storage portions in the case becomes extremely large. This poses a problem in arranging various functional components such as a floppy disk drive in the case. In addition, the first and second card storage portions have card insertion ports formed in a side surface of the case, and the card insertion ports are elongated in the lateral direction. As a result, the card insertion ports occupy a larger proportion of the side surface of the case. Therefore, when expansion connectors and the like are to be arranged on the side surface of the case, the arrangement of the connectors and the like are undesirably limited by the presence of the card insertion ports.
A portable computer has a display unit having a display. As disclosed in U.S. Pat. No. 5,103,377 issued to Kobayashi et al., Apr. 7, 1992 or U.S. Pat. No. 5,090,913 issued to Kobayashi, Feb. 25, 1992, this display unit is supported on the case to be pivotal between a closing position at which the unit covers a keyboard disposed on the upper surface of the case and an opening position at which the unit stands upright behind the keyboard. The display unit has leg portions extending toward the case, and the case has leg mount portions for receiving the leg portions. The leg portions are pivotally coupled to the leg mount portions via hinge mechanisms. In addition, the display is electrically connected to a circuit board, arranged in the case, via a cable. The cable is arranged between the leg portions and the leg mount portions. In this arrangement, the inner surface of the display unit including the leg portions and the inner surface of the case are covered with conductive layers. With this structure, noise from the cable for handling high-speed electrical signals can be sealed in the computer.
However, there are spaces between the leg portions and the leg mount portions, and the cable is exposed to the outside through these spaces. For this reason, in spite of the fact that the display unit and the case have an electromagnetic shield function, noise generated by the cable sometimes leaks to the outside of the computer through the spaces, posing a problem in realizing countermeasures against electromagnetic noise.